.top_nav {
    position: fixed;
    z-index: 1;
    background: (255, 255, 255, 0);
    width: 100vw;
    height: 6vh;
    display: flex;
    align-items: center;
  }

  .top_nav .logo {
    margin-left: 15vw;
    color: white;
    flex-grow: 5;
    font-size: 1.5rem;
  }

  .top_nav .logo i {
    font-size: 2rem
  }

  .top_nav .nav_ele {
    color: white;
    width: 5vw;
    font-size: 1rem;
  }

  .top_nav .nav_4 {
    margin-right: 25vw
  }


/* 小于1242时应用 */
  @media only screen and (max-width: 1242px) {
    .top_nav{
      height:5vh;
    }
    html {
      font-size: 135% !important;
    }
    .top_nav .logo {
      margin-left: 0vw;
     
    }
    .top_nav .nav_4 {
      margin-right: 0vw
    }
    .top_nav .nav_ele {
      width: 15vw;
    }

  }
/* 大于1242时应用 */
  @media only screen and (min-width: 1243px) {
    html {
      font-size: 100% !important;
    }
  }